On Thursday night, I reviewed the vast forces of National Youth Orchestra, playing big colourful works by European exiles in 1930s America. The following night, I was back at The Sage Gateshead to hear Northern Sinfonia’s clever little coda to this concert, performing contemporary American music as part of their Late Mix series, the huge orchestra and big tunes replaced by intricate chamber music that pushes the definition of music to its limits.

Steve Reich’s Violin Phase was originally written for one player and a pre-recorded tape, but was performed here in the version for four live violins. The repeating five-note motif began on a solo violin, a second player joins and the two parts gradually drift out of synch, mere fractions of a beat apart to begin with, and the other two players gradually work their way into the texture. The trick with listening to Reich’s music is to let the brain loose, and then the slowly shifting patterns of the interplay between the parts emerge; this requires absolute equality and balance between the players, and mostly this worked – although as the four players were (by necessity) facing each other, and I was sitting to one side of the hall, the balance wasn’t quite perfect. Watching the performance gave the piece an extra dimension; Iona Brown, leading with just the subtlest of nods and constant eye-contact, kept the whole piece together magnificently.

Even more concentration was required for the complexities of Elliott Carter’s Quintet for piano and strings, and violinist Kyra Humphreys introduced the piece with a little insight into the difficulties of the rehearsal process, when each player had had an extra stand with the full score on it, so that the five almost-independent parts could be fitted together through mind-boggling time changes (this also explained the intriguing photos that the players had posted on Twitter). The result is an extraordinary piece, dense, complex and difficult but also beautiful to listen to. The single-movement quintet opened in savage bursts of sound and tortuous variations as the same little motif is turned around and offset between the players. Gentle little fragments of sound, requiring an exquisite sense of timing, brought in a gentler central section, with long, slowly shifting chords and a surprisingly lyrical passage for the viola. The piece returns to a livelier mood to finish, with a rapid and melodic piano phrase, set against interjections from the strings, and just before the end, the five players come together briefly, for a moment before fragmenting again, the piano finishing just after the strings with one final high note. It would take great familiarity with the piece to know whether the players were perfectly accurate throughout, and there was an occasional look of panic, but as in the Reich, there was also an incredible sense of teamwork that was a privilege to watch, with all five musicians helping each other through the piece.

In stark contrast to the precision and intricacy of Carter’s quintet John Cage’s Fourteen derives its beauty from stillness, from random combinations of sound. A bowed piano – played with rosined fishing-line pulled against the strings – formed the central texture, dovetailing in and out of sustained notes played on string instruments. Brass players Marion Craig and Christopher Griffiths deserve particular mention for their long quiet notes, as do the audience, for their participation in the spellbinding silences that punctuate the work.

The programme was put together by The Sage Gateshead’s Composer in Association, David Lang, and was very much his personal snapshot of late 20th-century American music, something which became particularly clear on hearing his own piece these broken wings at the end of the concert; a piece in which elements of Steve Reich’s minimalism, Elliott Carter’s deep complexity and John Cage’s avant-garde experiments could all be clearly detected. It began with a tinkly brightness that was all the more surprising after Cage’s sonorous driftings, with an intricate, pretty piccolo passage, accompanied by high piano and glockenspiel. This tinkling, metallic texture was taken to its extreme in the second section, when the players were instructed to wander around in turn, dropping metal objects, against a soothing background of sustained notes; this could have been silly if not done carefully, but the musicians did it with a graceful dignity, and the unpredictability of the noise made by each falling object was an interesting extension of the work’s first theme. A final hypnotic dance-like section had the players swaying along, before it came to an abrupt stop, like a machine suddenly switched off.

The works on this programme may not be to everyone’s taste, and certainly if I had just heard them on the radio, I would not have appreciated them, but with the concentration that comes from a live performance I found them absorbing, fascinating, and in their own way, quite lovely.